Poems are personal things, not easy to decipher.
But no, not a former atheist or "apostate" atheist, if you get the reference.
Just a doubtful one, as you might be a doubtful Christian. On the fence, not sure, agnostic, unconvinced, open minded.
I'll try to shed a little light on the verses.
It's partly an honest exposition of a true atheist ethic, which you might find fully expressed in a beautiful, noble work like Thus Spoke Zarathustra.
If there is no god, I would say Nietzsche is the truest and bravest philosopher.
But if god is real, that makes things entirely different, leads to a totally different perspective and conclusions about those views. Puts a different light on the ethics which atheism would sanction if taken seriously.
The doubt in atheism is what leads the verses into considering the Christian view of these atheist virtues; the view of humanity as something to be shaped, where pride, ideology and status are justified by our biological nature and competition, as entirely free agents.
Without a god, we are and ought to be the pinnacle of creation, and humanity really is an arena and battleground for ideologies and competing claims for the right to shape and mold a passive humanity.
But, with God, we are his agents, and those things become grotesque caricatures of the sins of a fallen nature, rationalized by denial of god. The thing can go either way.
Finally, to round it out, the last part is about those half atheists, who are outwardly godless, but still retain moral ideas that make sense only if atheism is untrue. Atheists who adopt atheism in a half hearted way but retain all the objective moral demands of a God centered world. A theme I stressed in earlier posts.